Sources of pulses of light are used in a wide range of interference applications, for example in sensing or metrology apparatus such as strain, pressure or temperature sensors, spectroscopy apparatus, distance measurement apparatus or random number generation. The interference of pulses of light can also be used in quantum communications systems, for example in quantum key distribution (QKD) or measurement device independent QKD (MDI-QKD). In a quantum communication system, information is sent between a transmitter and a receiver by encoded single quanta, such as single photons. Each photon carries one bit of information encoded upon a property of the photon, such as its polarization, phase or energy/time. The photon may even carry more than one bit of information, for example, by using properties such as angular momentum.
There is a continuing need to enhance interference visibility in applications which use the interference of pulses of light.